D562: revset: drop optimization about reordering "or" set elements

[quark (Jun Wu)]

quark created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  The reordering optimization is more important for "and" than "or", given the
  implementation details about "addset" and "filteredset" - reordering "or"
  may help "__contains__" test but not iteration, reordering "and" could help
  both. We are going to simplify the tree to remove ordering information.
  Removing "or" reordering optimization would make things simpler.
  
  This effectively reverts https://phab.mercurial-scm.org/rHGc63cb2d10d6d5dc823853300f14fa9638bccfb68. It tracks back to the "orset"
  function added by the initial commit of revset (https://phab.mercurial-scm.org/rHGc9ce8ecd6ca116c60b5ddda6cdf5a1f1e723c27a).
  
  In the future, we might consider optimization at runtime (ex. do reordering
  and rewrites inside "orset").

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D562

AFFECTED FILES
  mercurial/revsetlang.py
  tests/test-revset.t

CHANGE DETAILS

diff --git a/tests/test-revset.t b/tests/test-revset.t
--- a/tests/test-revset.t
+++ b/tests/test-revset.t
@@ -2076,19 +2076,19 @@
       define)
     (or
       (list
-        ('symbol', '2')
         (range
           ('symbol', '0')
           ('symbol', '1')
-          follow))
+          follow)
+        ('symbol', '2'))
       follow)
     define)
   * set:
   <filteredset
     <spanset- 0:3>,
     <addset
-      <baseset [2]>,
-      <spanset+ 0:2>>>
+      <spanset+ 0:2>,
+      <baseset [2]>>>
   2
   1
   0
@@ -2569,69 +2569,6 @@
   1
   0
 
- 'A + B' can be rewritten to 'B + A' by weight only when the order doesn't
- matter (e.g. 'X & (A + B)' can be 'X & (B + A)', but '(A + B) & X' can't):
-
-  $ try -p optimized '0:2 & (reverse(contains("a")) + 2)'
-  * optimized:
-  (and
-    (range
-      ('symbol', '0')
-      ('symbol', '2')
-      define)
-    (or
-      (list
-        ('symbol', '2')
-        (func
-          ('symbol', 'reverse')
-          (func
-            ('symbol', 'contains')
-            ('string', 'a')
-            define)
-          follow))
-      follow)
-    define)
-  * set:
-  <filteredset
-    <spanset+ 0:3>,
-    <addset
-      <baseset [2]>,
-      <filteredset
-        <fullreposet+ 0:10>,
-        <contains 'a'>>>>
-  0
-  1
-  2
-
-  $ try -p optimized '(reverse(contains("a")) + 2) & 0:2'
-  * optimized:
-  (and
-    (range
-      ('symbol', '0')
-      ('symbol', '2')
-      follow)
-    (or
-      (list
-        (func
-          ('symbol', 'reverse')
-          (func
-            ('symbol', 'contains')
-            ('string', 'a')
-            define)
-          define)
-        ('symbol', '2'))
-      define)
-    define)
-  * set:
-  <addset
-    <filteredset
-      <spanset- 0:3>,
-      <contains 'a'>>,
-    <baseset [2]>>
-  1
-  0
-  2
-
 test sort revset
 --------------------------------------------
 
diff --git a/mercurial/revsetlang.py b/mercurial/revsetlang.py
--- a/mercurial/revsetlang.py
+++ b/mercurial/revsetlang.py
@@ -467,9 +467,6 @@
         flushss()
         if len(ts) == 1:
             return ws[0], ts[0] # 'or' operation is fully optimized out
-        if order != defineorder:
-            # reorder by weight only when f(a + b) == f(b + a)
-            ts = [wt[1] for wt in sorted(zip(ws, ts), key=lambda wt: wt[0])]
         return max(ws), (op, ('list',) + tuple(ts), order)
     elif op == 'not':
         # Optimize not public() to _notpublic() because we have a fast version



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